Reporting of D-dimer testing in venous thromboembolism diagnostic management studies: a scoping review

BACKGROUND: D-dimer testing is widely integrated into diagnostic algorithms for venous thromboembolism (VTE). However, the lack of standardization across D-dimer assays and reporting may limit the comparability of study findings. OBJECTIVES: To summarize reporting of essential characteristics of D-dimer testing in VTE diagnostic management studies. METHODS: We systematically searched MEDLINE and Embase from January 1999 to August 2024 for VTE diagnostic management studies that evaluated diagnostic algorithms, including D-dimer testing, and followed patients for ≥ 4 weeks after VTE was excluded. The primary outcome was reporting of D-dimer assay characteristics. Secondary outcomes were reporting of patient numbers and failure rates per assay. RESULTS: Of 9670 articles screened, 58 studies were included: 36 (62%) enrolled patients with suspected pulmonary embolism, 21 (36%) with suspected deep vein thrombosis, and 1 with suspected VTE. Sample sizes ranged from 191 to 5400; follow-up was 1 to 6 months. Assay name was fully reported in 52 of 58 studies (90%), manufacturer in 49 of 58 (85%), unit magnitude in 42 of 46 (91%), and the unit type in 8/46 (17%). The detection limit was reported in 3 of 58 studies (5.2%); other analytical performance parameters were unreported. Nineteen quantitative assays were used across 19 combinations of thresholds and unit magnitudes. Of 17 studies using multiple assays, 9 reported patient numbers per assay, and 1 reported failure rate per assay. CONCLUSION: Key characteristics of D-dimer testing were inconsistently reported in VTE diagnostic management studies. While assay name, manufacturer, unit magnitude, and thresholds were often included, unit type and assay-specific data were frequently omitted. Minimum reporting standards for D-dimer testing are needed for VTE diagnostic management studies.